The circular economy requires that we know what a product is made of, that we can control that it is not a fake, and that we know how to recycle it. This requires a digital twin of each product where the information is stored and that we can access using a smartphone. The creation of digital twins requires a connection between the physical and digital worlds, which in turn requires that all objects have a unique identifier valid in both domains. The realization of the intrinsic potential of creating digital twins of individual products that link physical and digital identities in turn requires that the physical identifier is truly unique and that it cannot be copied. Furthermore, the physical identifier should not interfere with the product lifecycle, in particular recyclability, as this would be a potential blocker in a circular economy. Here, we present a physical identifier on the basis of a physical unclonable function (PUF) made from polymer nanoparticles and imbedded in a polymer laminate, where all components can be made from the same recyclable material. Such materials are commonly used for packaging in the fragrance and cosmetics industry. The development of the PUF system is presented, and each PUF was validated using a proprietary smartphone application with a QR code as a common pattern defining the PUF canvas. The functionality of the PUF was demonstrated across product types as diverse as lateral flow assays and construction materials. We conclude that polymer nanoparticle PUFs are a viable and directly recyclable solution to document authenticity and inform on recyclability of polymers in the circular economy.